This invention relates to a heat-sensitive recording material and more particularly to a heat-sensitive recording material in which a synthetic paper is used as a base sheet and which is superior in recording runnability and recording quality, and gives recorded materials useful as a second original for diazo print.
According to the development of manufacturing technology of semiconductor, a wide single thermal head could be manufactured efficiently at a low cost as a thermal head used in heat-sensitive recording system. Since thermal plotters equipped with the head can print wide letters with a high printing speed and require no maintainance, they have gradually supplanted conventioanl pen plotters.
Further, images recorded by these plotters are mainly the figures drawn by CAD and used as the originals for diazo duplication. Accordingly, as the recorded materials are supplied as the secondary originals for diazo duplication, a somewhat transparency is required for the medium. A semitransparent or transparent heat-sensitive recording material in which a transparent film is used as the support has been required as a medium for heat-sensitive recording system.
On the other hand, the wide thermal plotter mentioned above is different from usual heat-sensitive equipments such as facsimile and the like. In the case, the medium is generally transferred by driving a driving roll equipped downstream of the nip portion between the thermal head and the platen roll as shown in FIG. 1. When the recording is made on a heat-sensitive recording material using a transparent film as the support in such a thermal plotter, the driving roll idles at the nip portion between the driving roll and the plate usually Teflon-lined and troubles of abnormal transfer of the heat-sensitive recording material occur in a high frequency.
The cause of the trouble can be assumed that, though the reverse surface of the heat-sensitive recording material using a transparent film as the support is usually not processed or back-coated to some g/m.sup.2, the support has a very high smoothness compared to paper and common synthetic paper even if back-coated, and therefore the reverse surface of the heat-sensitive recording material adheres tightly with the plate surface at the nip portion between the driving roll and the plate so that the driving roll idles. As a countermeasure for this trouble, it can be considered that a pigment of relatively large particle size is added to the back coat layer to roughen the reverse surface of the heat sensitive recording material. However, this method lowers largely transparency, though it shows some effect on the improvement of runnability and it cannot be a practical means for improvement. When a paper-based support of high transparency, for example, a glassine paper, is used, the recording surface is also rough and therefore the heat-sensitive recording layer formed on it becomes also rough to deteriorate the recording quality disadvantageously.
The object of the present invention is to provide a heat-sensitive recording material which is superior in recording runnability and recording quality and gives recorded materials useful as a second original for diazo print.